Zinc carbonate, stable nano zinc oxide, and methods of making the same

A method of preparing a nano zinc oxide, comprising:

• a) preparing an aqueous zinc ammonia carbonate solution from a zinc source, ammonia and carbon dioxide, wherein the ammonia and the carbon dioxide are present in a ratio by moles or by weight effective to dissolve the zinc in the zinc source;
• b) removing one or more metal impurities from the solution;
• c) injecting CO2 into the zinc ammonia carbonate solution at a pressure up to about 40 psi and a temperature of approximately 5 to 50° C.;
• d) heating a resulting slurry to a temperature of about 90° C. or more until the ammonia is substantially absent from the solution to obtain zinc carbonate;
• and
• e) drying the zinc carbonate at a temperature from around 150° C. to 400° C. for a length of time that removes water and at least some of the CO2 and provides the nano zinc oxide, wherein the nano zinc oxide has a surface area-to-mass ratio of 60-120 m2/g when freshly made and above 40 m2/g after 12 months.